1. Field of the Invention
The present invention relates to solar powered outdoor lighting, and more specifically, to high-brightness solar powered outdoor lighting incorporating specialized control circuitry for maximizing battery runtime.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Solar powered outdoor lighting is well known in the art. Such lights typically utilize a rechargeable battery that receives its charge from solar panels during the daytime and expends its charge during the nighttime by powering the light source. Depending upon the light source, the battery may or may not last for the entire period of darkness.
With the advent of LEDs, battery runtime for outdoor lighting has improved over older incandescent devices. However, early LEDs sacrificed luminosity for the reduced current demand. These LEDs were often not sufficiently bright enough to be useful for other than decorative applications. To be useful for security or safety applications, such lights needed to be substantially brighter.
Recent developments in LED technology have resulted in lighting having substantially higher luminosity. Use of high-brightness LEDs allows for outdoor lighting that is bright enough to be practical for a host of applications (decoration, security, safety, etc.). Consequently, this higher light output again translates to higher current demands and reduced battery runtime. Thus, although the lighting is highly efficient relative to early incandescent bulbs, the current demand is beginning to rival the same.
In an effort to improve runtime with high-brightness LEDs, designers have resorted to increasing the overall battery capacity by increasing the number of cells or by using exotic chemical formulations having higher energy densities. However, increasing the number of cells results in larger and less aesthetically pleasing lighting fixtures. Also, utilizing higher energy-density battery formulations increases the cost of the battery and, consequently, the cost of the lighting fixture. What is needed is an improved control means for utilizing the available standard rechargeable battery capacity to efficiently power a high-brightness LED lighting fixture without increasing the fixture's physical size.